As well known, many techniques and apparatus exist for making tissues and biocompatible artificial membranes. In particular, the main known techniques provide the production of the above described artificial tissues by extrusion, or by spraying fluid substances. More in detail, the spraying techniques provide the deposit of a polymeric solution of synthetic origin by overlapping the polymeric solution in diluted form and a non-solvent, for example water, to each other. To this purpose a sprayer is used which sprays both substances in an alternated way, or, alternatively, two sprayers are used that deliver the two substances at the same time. The substances are deposited on a support body which has the same geometry of the desired tissue products or artificial membranes.
An example of an apparatus for making such membranes by spraying is disclosed in WO200405477. The apparatus uses a plurality of sprayers, each of them drawing from a respective reserve a component of the biological mixture. A cylindrical support element is then arranged on which the fluid substances supplied by the sprayers are deposited, in order to make a coating that forms the desired membranes. The cylindrical support element can kinematically rotate about a fixed rotation axis, whereas the sprayers are moved by a carriage that makes a translational movement along an axis that is substantially parallel to the rotation axis of the cylindrical support element. This way, the fluid substances supplied can deposit on the whole surface of the support element.
However, this solution, as it can be understood, is applicable only in case the membranes to make have a relatively simple and regular shape with surfaces presenting a wide radius of curvature and not too suddenly variable. Such membranes should also have substantially axisymmetric shape, in order to keep a constant spraying flow during the rotation of the support element.
A similar apparatus is disclosed in WO2010136983. Even in this case, the apparatus is used for making a biocompatible structure that allows regenerating biological tissues with simple shape. Notwithstanding the above, the apparatus as above described for making tissues or biocompatible artificial membranes cannot provide anatomical. prostheses with complex shape, such as concave or convex heart patches, ellipsoidal cardiac chambers, patches for calcaneal ulcers, or portions of organs.
U.S. Pat. No. 5,376,117 describes a breast prosthesis for subcutaneous implants. The prosthesis consists of an outer shell comprising a non-porous layer of biocompatible polymeric material and a porous outer layer that coat wraps the non-porous layer. The outer layer is made by electrostatic deposit of biocompatible polymeric fibers on the inner layer. Once obtained the three-dimensional structure, the prosthesis is overturned and arranged on a spindle that is rotated about its own axis, in order to make the convex side of the prosthesis.
A breast prosthesis obtained by a process similar to that described in U.S. Pat. No. 5,376,117 is disclosed also in WO2010/059834. However, both processes, as described in U.S. Pat. No. 5,376,117 and WO2010/059834, are not suitable for the production of tissues and biocompatible artificial membranes with complex shape and with small tolerances, since they cannot ensure an accurate definition of the modelled forms.